<?php
/**
 * Created by PhpStorm.
 * User: User
 * Date: 2017/10/11
 * Time: 8:32
 */
class Shape
{
    public function getArea(){}
  public  static function  getPi(){
      return 3.14;
  }

}
class  Rectangle extends Shape
{
    private $instance;
    private $width, $height;
    public function __construct($width,$height)
    {
       // $this->height=$height;
        //$this->width=$width;
    }
    public function  get0bj(){
        if(Rectangle::instance==null){

        }
        return new Rectangle();
    }
    public function  getArea()
    {
        return $this->width*$this->height;
    }
}
$a=Rectangle:: get0bj();
$b=Rectangle::get0bj();
